ARS | Publication request: The effects of diet on herbivory by a predaceous lady beetle

Submitted to: Biocontrol Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 14, 2010
Publication Date: January 1, 2011
Citation: Lundgren, J.G., Moser, S., Hellmich Ii, R.L., Seagraves, M. 2011. The effects of diet on herbivory by a predaceous lady beetle. Biocontrol Science and Technology. 21(1):71-74.

Interpretive Summary: Although best appreciated for their ability to eat insect pests, it has been recently discovered that lady beetles also eat plant tissue. Indeed, most beneficial predators eat both prey and non-prey foods, and determining the factors that affect omnivory in these insects will be important to using them in biological control of crop pests. Here, we tested whether a native lady beetle, Coleomegilla maculata, fed only insect prey is more likely to eat plant tissue than lady beetles fed a mixed diet. Our results reveal that this lady beetle consumes 2-3 times more plant tissue when fed only prey, and suggests that plant material is providing some key nutrients lacking in prey-only diets. There are implied implications of this behavior for integrating biological control in cropland planted to varieties with plant-incorporated insecticides.

Technical Abstract: Prey and non-prey foods often contain different nutrients, and optimal diets for predatory insects often contain both food classes. We tested whether late instars of Coleomegilla maculata DeGeer (Coleoptera: Coccinellidae) reared on prey- Acyrthosiphon pisum Harris (Hemiptera: Aphididae) or eggs of Ostrinia nubilalis Hübner (Lepidoptera: Crambidae)- consumed more plant tissue (pinto bean seedlings) than those fed on a mixed diet (containing pollen substitute and various prey-based components). Larvae fed the different diets developed at varying rates, and attained different weights after 9 d of feeding. Prey-fed treatments consumed 2- to 3-fold more plant tissue than those fed a mixed diet. This research suggests that plants provide nutrients that are missing from some prey-only diets, and that coccinellids consume these plant-based nutrients when they become available.